/* =============================================================
 * Your Grandmother's guide to Algorithms
 * =============================================================
 *
 * Copyright (c) 2007, Saverio Miroddi
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright 
 *       notice, this list of conditions and the following disclaimer in the 
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the SaverioMiroddiSoftware nor the names of its 
 *       contributors may be used to endorse or promote products derived from 
 *       this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER 
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *  
 * ---------------------------
 * Join.java
 * ---------------------------
 *
 */
package algos;

import dbobjects.Condition;
import dbobjects.tables.Table;

/**
 * @author Saverio Miroddi
 */
public class Join {
	public static final int INNER = 0;
	public static final int LEFT_OUTER = 1;
	
	public static final int FORCE_NESTED = 10;

	private IAlgo joinAlgo;
	
	public Join(Table leftTable, Table rightTable, Condition cond, int type) {
		this(leftTable, rightTable, cond, type, false);
	}
	
	/**
	 * Service constructor.
	 * 
	 * @param forceNested
	 *            if true, force nested join.
	 */
	public Join(Table leftTable, Table rightTable, Condition cond, int type,
			boolean forceNested)
	{
		if (forceNested) {
			joinAlgo = new NestedLoopsAlgo(leftTable, rightTable, cond, type);
		}
		else {
			switch(cond.operator) {
			case Condition.OP_B:
			case Condition.OP_BE:
			case Condition.OP_G:
			case Condition.OP_GE:
				joinAlgo = new SortMergeAlgo(leftTable, rightTable, cond, type);
				break;
			case Condition.OP_EQ:
				joinAlgo = new HashAlgo(leftTable, rightTable, cond, type);
				break;
			case Condition.OP_NE:
				joinAlgo = new NestedLoopsAlgo(leftTable, rightTable, cond, type);
				break;
			default:
				throw new Error();
			}
		}
	}


	public String[] getCurrentRow() {
		return joinAlgo.getCurrentRow();
	}

	public boolean next() {
		return joinAlgo.next();
	}	
}
